复合酶制剂在玉米淀粉湿法加工中的应用

玉米淀粉加工复合酶制剂是玉米淀粉加工专用酶制剂,主要由纤维素酶、木聚糖酶等组成.为了探讨复合酶制剂在玉米淀粉湿法加工过程中的工艺效果,通过复合酶制剂在玉米纤维洗涤过程中的应用,考察经过酶反应处理后玉米粉浆粘度和纤维吸水性的变化,以及淀粉和蛋白质收率、蒸汽消耗量等指标.结果表明,酶制剂能够将玉米的胚乳淀粉细胞壁及种皮纤维...     

酶制剂热稳定性的研究进展

很多研究结果表明,在单胃动物日粮中添加以非淀粉多糖酶为主的复合酶制剂,可显著提高畜禽营养物质的消化率,从而提高单胃动物的日增重和饲料转化率。非淀粉多糖酶可以降解日粮中单胃动物本身不能消化的非淀粉多糖(木聚糖、β-葡聚糖、果胶等),同时释放被细胞壁包裹的营养物质,并可降低食糜粘度,促进营养物质在胃肠道的消化吸收。制粒可以破碎细胞壁,促进粗纤维、粗蛋白质等营养物质的消化吸收,提高饲料转化率。但是在制粒过程中,由于蒸汽的输入和压模机的摩擦,温度可达60~100℃;而温度的升高将导致酶的失活,并且随着温度的升高和时间延长,酶…     

三种改性方法对青香蕉淀粉物化性质的影响

为了探求一种既尽可能保留青香蕉淀粉的天然特性,又能改善其加工特性的改性方法,对比了复合酶法、乳酸发酵法和挤压膨化法对青香蕉淀粉特性的影响。结果表明：三种改性方法中,复合酶法能够显著提高抗性淀粉的质量分数;通过比较三种改性淀粉的理化特性,复合酶法和乳酸发酵法使结晶度由18.13%分别增加到20.19%和22.06%,而挤压膨化法使结晶度大幅下降至2.16%。复合酶法淀粉的分子解聚程度低,能较好保持原淀粉的颗粒形态,且有助于提高淀粉糊的热稳定性、冷稳定性和凝沉性。而乳酸发酵法和挤压膨化法使热稳定性降低,凝沉性减弱,但能够提高冷稳定性;加工特性研究表明,复合酶法对香蕉原淀粉的色泽影响较小,有助于改善淀粉糊的透明度,提高香蕉淀粉的感官品质。挤压膨化改性淀粉在透明度、溶解度和吸水性方面均有所改善。而乳酸发酵改性对冻融稳定性的影响较小。综上而言,复合酶法是较理想的改性方法。     

复合酶对高浓度淀粉乳液化的影响

以黏度为指标,研究了复合酶对高浓度(45%)玉米淀粉乳液化的影响。同时分析了不同液化条件对产物的影响,包括液化液中还原糖含量、摩尔质量分布、小分子糖组成与含量的变化。结果表明:复合酶有利于降低45%淀粉乳的液化黏度,提高45%淀粉乳液化过程中的还原糖含量,降低平均摩尔质量,液化液的摩尔质量分布更加均匀。液化液DE值分别为10、15、20时,与只加耐高温淀粉酶相比,复合酶液化时,45%液化液平均摩尔质量分别降低了15.2%、26.9%和5.6%;小分子糖组成不变,各麦芽低聚糖含量变化不大,说明复合酶有效降低高浓度淀粉乳黏度的同时,对液化产物的影响不大。     

1-甲基环丙烯对硬溶质型桃果实细胞壁多糖降解特性的影响

以硬溶质型桃"晚湖景"为试材,20℃下用1μL/L 1-甲基环丙烯(1-MCP)密闭处理24h,研究1-MCP处理对细胞壁降解过程中多糖组分变化、单糖解离特性以及细胞壁多糖降解相关酶的影响。结果表明:1-MCP处理可以明显抑制硬溶质型桃果实硬度的下降,降低乙烯释放量。1-MCP处理的硬溶质型桃果实中CDTA-2、Na2CO3、KOH和CWM-残渣组分在贮藏过程中下降速率都明显低于未处理果。1-MCP处理能延缓CDTA溶性果胶多糖的解离。同时还抑制了Na2CO3溶性果胶多糖中半乳糖醛酸和鼠李糖构成的主链和阿拉伯糖、半乳糖支链的降解,对半纤维素和纤维素多糖成分降解有一定程度的抑制作用。1-MCP处理可能通过抑制参与细胞壁多糖降解相关酶的活性,从而抑制硬溶质型桃果实细胞壁多糖降解及单糖解离,达到延缓果实软化的目的。     

冬枣后熟软化过程中细胞壁多糖降解特性的研究

研究冬枣采后成熟过程中,果实硬度、呼吸强度、细胞壁物质和不同细胞壁多糖组分的单糖含量的变化。在不同的贮藏阶段(0 d和60 d)提取果实的细胞壁物质和8种细胞壁多糖组分,采用离子色谱法分析部分细胞壁多糖组分的单糖组成。结果表明,随着贮藏期的延长,果实硬度缓慢下降,呼吸强度逐渐升高。后熟过程中果肉细胞壁多糖组分量减少,贮藏前、后Na2CO3-1、CDTA-1和KOH-1溶性多糖量的减少率均呈显著差异(P0.01),其中Na2CO3-1和CDTA-1溶性果胶细胞壁多糖减少尤为显著,表明冬枣果肉软化与CDTA和Na2CO3溶性多糖组分的降解密切相关。Na2CO3和CDTA溶性果胶多糖的单糖组分中,富含阿拉伯糖。贮藏前、后阿拉伯糖降解明显,表明支链的降解促进了果实的软化。半纤维素组分(KOH-1、KOH-2、KOH-3细胞壁多糖组分)在成熟过程中下降,但贮藏前、后KOH溶性半纤维素多糖分子质量峰值几乎没有变化,推测其参与果实软化的进程较复杂。     

植物细胞壁多糖降解中相关辅酶的研究

文章系统的研究了在植物细胞壁多糖支链的降解过程中起关键作用的辅酶,对辅酶的来源、分类及作用等进行了阐述,为植物细胞壁多糖的完全降解提供了理论依据。     

黑曲霉F27复合酶对大麦胚乳降解作用的研究

本文研究了黑曲霉Ｆ２７固体曲浸提的酶液对大麦胚乳的降解作用过程，并进行了显微摄影。５０℃黑曲霉Ｆ２７中的复合酶（以β－葡聚糖酶和蛋白酶为主）能有效地作用大麦胚乳细胞壁，使胚乳细胞内含的淀粉颗粒变得疏松并呈游离状态，从而与淀粉水解酶系更加充分地接触，然后升温到６５℃，达到降解。     

细胞壁对果实质地影响机制的研究进展

果实质地的改变严重影响采后果实的贮藏运输及其商品价值。而采后果实质地的改变通常认为是由于果实细胞初生壁和胞间层组织中的多糖降解,引起细胞壁超微结构改变所导致的。同时细胞壁多糖降解和多聚物化学键的改变,会进而引起细胞分离、软化、溶胀,改变细胞膨压,从而影响果实质地。多糖降解过程受到一系列细胞壁酶的协同作用,不同酶在果实质地变化的各阶段作用不同,而且各种酶活性变化在不同品种的果实中表现不同。本文主要对细胞壁多糖降解以及其相关酶对果实质地变化的影响进行了系统的分析与展望,总结了果实成熟软化中细胞壁的降解机理,为更好地进行果实贮藏、保鲜及加工提供理论依据。     

微波预处理对玉米淀粉液化的影响

以黏度和还原糖含量为指标,探讨了微波预处理对高浓度玉米淀粉液化的影响,并对其机理进行了分析。结果表明:经微波预处理后,高浓度玉米淀粉在糊化、液化过程中的粘度低于对照,而还原糖含量明显高于对照,为高浓度玉米淀粉的液化创造了更好的条件。其主要机理可能是:微波预处理使玉米淀粉颗粒表面变得粗糙,且出现孔洞,增加了颗粒的比表面积,同时颗粒结构变得疏松,结晶度下降,导致在升温糊化、液化过程中酶对淀粉颗粒的降解作用更加明显;另外,微波预处理也可能使部分淀粉链发生了一定程度的降解。     

Preparation of Passion Fruit Puree by Flash Vacuum-Expansion

ABSTRACT Purple passion fruit were processed by flash vacuum‐expansion in comparison with a single‐strength juice. A puree was obtained with about 50%/fruit weight yield, which is 2‐fold that obtained for the reference juice. Color and cell‐wall polysaccharides of the products were analyzed, and their rheological properties were investigated. The red‐purple puree was enriched in anthocyanins and alcohol‐insoluble residue. The puree had higher consistency and viscosity, which was related to its alcohol‐insoluble residue and starch contents.     

COLOR, POLYPHENOLOXIDASE, AND SENSORY CHANGES IN BANANA JUICE AS AFFECTED BY HEAT AND ULTRAFILTRATION

A study was conducted to determine the effects of banana maturity (less mature; maturity stage 3, more mature; maturity stage 7), heat treatment of banana puree, heat pasteurization of juice, and ultrafiltration (UF) of juice on color, polyphenoloxidase (PPO) activity, and flavor of puree and juice. Heating puree to 90C inactivated PPO and reduced browning in puree and juice, especially in puree from more mature bananas which had greater PPO activity. PPO activity decreased considerably during cold-setting and filtration of juice, and was not detectable in unheated, pad-filtered juice from less mature bananas. UF of juice through a 10,000 mwco membrance, but not a 30,000, removed all PPO activity and reduced juice browning. Pasteurization of juice (hot fill at 90C) increased browning, but not as much as PPO activity in the puree. Pasteurization had no effect on juice flavor if the puree had been heated to 90C previously as puree, but altered the flavor (i. e., more cooked banana flavor) of juice that had not been previously heated to 90C. Pasteurized juice that had not been heated to 90C as puree had similar flavor (no significant difference) as pasteurized juice that had been heated to 90C as puree.     

VISCOSITY REDUCTION AND PREVENTION OF BROWNING IN THE PREPARATION OF CLARIFIED BANANA JUICE1

Experiments were conducted to determine the effects of commercial enzyme preparations on viscosity reduction and filterability of banana juice, and the effectiveness of various anti-browning treatments on clarified juice. Two different combinations of pectinase, cellulase and hemicellulase were more effective in reducing viscosity and improving filterability of both green and ripe banana purees than a pectinase, galactomannanase or cellulase after incubation periods of 3, 6 and 9 h. An alpha-amylase was not effective in reducing viscosity as compared to the control, even of green banana puree high in starch. Potassium metabisulfite (100 mg/L) was more effective in producing a light colored juice with stable color than two heating methods (heating whole, unpeeled bananas at 100°C for 11 min.; heating puree at 80°C for 1–2 min) and ascorbic acid (470 mg/L). Polyphenoloxidase was active in the clarified juices treated with ascorbic acid and the control, and both darkened over time. Sensory analysis indicated that all the juices had similar banana flavor intensity.     

Change in aromatic components of banana during the preparation process of juice and microcapsule powder

Based on the importance of pleasant aroma on quality of banana products, a study was carried out on how the aromatic profile of banana is affected when fresh ripe banana is processed into puree, clear juice, microcapsulated banana powder and reconstituted juice. Solid‐phase micro‐extraction extraction and gas chromatography–mass spectrometry identification showed that puree, clear juice and reconstituted juice possessed the similar aromatic profiles with esters as the crucial components contributing the most to the characteristic aroma. Components of secondary importance to the aroma were contributed by the carbonyl fractions, followed by alcohols and hydrocarbons and elemicin. Only four compounds were retained on the surface of the microcapsulated banana powder. Primary component analysis extracted two principal components that exhibit 100% contribution to the total variance of the data set. Aroma profile of banana puree, clear banana juice and the reconstituted banana juice show no significant difference, with esters as the decisive components of the aroma and isoamyl butyrate as the major constituent of the esters, while the compounds responsible for the characteristic aroma were hardly detected from the microcapsulated banana powder, indicating that the main volatile components can be effectively encapsulated through microcapsulation.     

澄清型香蕉汁的挥发性物质研究

利用固相微萃取 (SPME)法浓缩香蕉汁香味物质 ,用气相色谱 质谱 (GC MS)检测、鉴定其中的各种挥发性成分。结果表明 ,SPME法可用于香蕉汁香味成分的快速鉴定。与新鲜香蕉相比 ,香蕉汁保留了新鲜香蕉特征性香味成分如乙酸异戊酯、丁酸异戊酯、异戊酸异戊酯、异榄香素等总含量的 71 5 0 %,表明果汁保留了香蕉鲜果主要风味。但果汁中醇类、有机酸与羰基化合物含量增多 ,并出现了二甲硫醚、呋喃等热加工产物。     

Enzymatic liquefaction of jicama (Pachyrhizus erosus) tuberous roots and characterization of the cell walls after processing

Enzymatic liquefaction of jicama (Pachyrhizus erosus) tuberous roots increases the yields of juice. Jicama tuberous root was disintegrated by Pectinex Ultra SP-L (≥3800 U/mL). Juice volume, glucose and alcohol insoluble solids (AIS) were determined. Remaining cell walls were characterized by infrared spectroscopy. AIS were destarched using amylolytic enzymes and analyzed by gas chromatography. The aim of this research was to evaluate the effect of enzymatic liquefaction of jicama tuberous root on juice volume, glucose and quantification and characterization of alcohol insoluble solids (AIS). The highest volume of juice was 980 mL/kg tuberous root. The range for maximum glucose was 58.0–75.8 g/kg tuberous root and the lowest for residual AIS was in the range of 15.5–24.6 g/kg tuberous root after 10 h with 0.024 mL/g of enzyme per kg at 40 °C. Infrared spectra showed signals corresponding to low methoxylated pectins, proteins and starch. Destarched jicama cell walls gas chromatograms revealed a decrease in sugars after liquefaction except in xylose, glucose and mannose which increased as a result of this process. Hydrolyzed jicama tuberous root is a good source of high glucose syrups and destarched cell walls may need enzyme rich in xylanase to reduce residue further.     

Comparison of Oligo- and Polysaccharides Formed from Starch During Processing of Sweet Potato Puree by Endogenous and Exogenous Enzyme Treatments

Hydrolysis patterns of starch were monitored during production of sweet potato puree (Jewel variety) using high performance size exclusion chromatography. A wide range of polysaccharides from large molecular size to simple sugars was observed. Lye peeling, prior to pureeing, induced partial hydrolysis by native enzymes due to gelatinization of starch from heat and alkali. Native enzymes were inactivated by steam injection (105°C for 5 min) and the puree treated with Bacillus subtilis alpha-amylase and Tenase, a thermostable alpha-amylase. Bacillus subtilis alpha-amylase produced a narrower molecular size range of polysaccharides during hydrolysis relative to Tenase. The average molecular size distribution of amylolysis end products from the native and exogenously treated systems differed. Specific lower molecular weight oligosaccharides formed during the final stages of amylolysis.     

Post-harvest Processing of Banana: Opportunities and Challenges

Banana has a special place in the daily diet of millions of people around the world for sustenance and nutrient enrichment. Some of the popular food uses of banana are chips, raw ripened fruit, cooked green banana, fermented and unfermented beverages, juice, puree, dried flour for bakery and infant formula food. Banana is also used as a starch source for various chemicals and packaging materials. The storability and functional properties of these products can be altered by the application of various innovative food processing technologies. This review article focuses on different banana products, their potential for non-conventional uses and associated prospective novel processing techniques for value addition and preservation.     

Optimization of Apple Juice Production by Single Pass Metallic Membrane Ultrafiltration

Apple puree was treated with various amounts of commercial liquefaction enzyme (0%– 0.066%) for 2 hr at 50°C. To produce clarified juice purees were pumped through a metallic oxide membrane ultrafiltration system, consisting of 3.27 ft² (0.304 m²) of membrane coated internally onto a l–1/4 inch (i.d.) × 10 ft (3.12 cm × 3.04 m) sintered stainless steel tubing. All enzyme treatments reduced viscosity 70–80% within 1 hr but steady state flux increased with higher concentrations of enzyme. Alcohol insoluble solids (AIS) and total pectins of the apple puree after enzyme treatment decreased as enzyme concentration increased to 0.044%. A large scale system, l–1/4 inch (i.d.) × 120 ft (3.12 cm × 36.48 m), was operated at 86% juice yield with minimal pressure drops as predicted by a mathematical model.     

果浆酶和植物复合水解酶对香蕉果浆的酶解效果比较

研究了果浆酶Pectinex xxl和植物复合水解酶Viscozyme L的酶添加量、酶解温度、酶解时间对香蕉果汁得率、澄清度、粘度和浊度的影响,确定了Pectinex xxl和Viscozyme L酶解香蕉浆的最佳工艺。在此基础上通过对酶解后香蕉浆和香蕉汁的成分和特性分析,对两种酶的酶解效果进行了比较。结果表明,Viscozyme L降解香蕉浆中的果胶和纤维素的活力较强,酶解效果较佳。